One of the most common questions people in the UK ask when considering hiring a private investigator (PI) is, "How much does a PI cost for a day?" This is an important question, especially for people or businesses that need investigative services but want to know how much they might cost. The price of hiring a private investigator for just one day can vary a lot based on several things, such as the type of investigation, the level of expertise needed, the location, and any other services that may be needed.